U.S. patent application number 12/491302 was filed with the patent office on 2010-12-30 for switching mechanism for camera.
This patent application is currently assigned to VTC Electronics Corp.. Invention is credited to Julian Lin, Tai-Kuo Wang, Wen-Chi Wang.
Application Number | 20100328796 12/491302 |
Document ID | / |
Family ID | 43380431 |
Filed Date | 2010-12-30 |
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United States Patent
Application |
20100328796 |
Kind Code |
A1 |
Wang; Tai-Kuo ; et
al. |
December 30, 2010 |
SWITCHING MECHANISM FOR CAMERA
Abstract
A switching mechanism for a camera includes: a control unit; a
driving device coupled with and actuated by the control unit; a
first gear set coupled with the driving device; a second gear
coupled with the first gear set and centrally provided with a
rotary shaft having a shaft hole formed with threads; a spindle
being female-connected to the shaft hole and which has an axial
surface formed with outer threads corresponding to the threads of
the shaft hole, thus allowing the second gear to move along and
relative to the spindle; and a translation member positioned
perpendicular to the spindle and provided with a rack for engaging
with the second gear and thus driving the translation member to
move perpendicular to the spindle. The second gear drives or does
not drive the rack as the engagement therebetween is made or
broken.
Inventors: |
Wang; Tai-Kuo; (Taipei City,
TW) ; Wang; Wen-Chi; (Taipei, TW) ; Lin;
Julian; (Taipei, TW) |
Correspondence
Address: |
ROGER H. CHU
19499 ERIC DRIVE
SARATOGA
CA
95070
US
|
Assignee: |
VTC Electronics Corp.
Taipei
TW
|
Family ID: |
43380431 |
Appl. No.: |
12/491302 |
Filed: |
June 25, 2009 |
Current U.S.
Class: |
359/889 |
Current CPC
Class: |
G02B 26/007
20130101 |
Class at
Publication: |
359/889 |
International
Class: |
G02B 5/22 20060101
G02B005/22 |
Claims
1. A switching mechanism for a camera, comprising: a control unit;
a driving device coupled with and actuated by the control unit; a
first gear set coupled with the driving device; a second gear
coupled with the first gear set and being centrally and fixedly
provided with a rotary shaft having a shaft hole formed with a
plurality of threads; a spindle around which the second gear is
mounted via spindle being female-connected to the shaft hole of the
second gear, the spindle having an axial surface formed with a
plurality of outer threads corresponding to the threads of the
shaft hole so that the second gear is movable along the spindle;
and a translation member positioned perpendicular to the spindle
and provided with a rack for engaging with the second gear; wherein
the driving device, when actuated by the control unit, drives the
first gear set so that the second gear is driven threadingly by the
first gear set to move linearly along the spindle as the threads of
the shaft hole of the rotary shaft of the second gear match with
the outer threads on the surface of the spindle, through proper
spatial arrangement, the second gear, when moved to a first
predetermined position along the spindle, engages with the rack of
the translation member so that the rack drives the translation
member to move perpendicularly to the spindle, wherein the second
gear, when further moved to a second predetermined position along
the spindle, is disengaged from the rack of the translation member
so that the translation member stops moving.
2. The switching mechanism of claim 1, wherein the translation
member is coupled with a filter and a glass plate so that, when the
translation member is driven by the rack, the filter and the glass
plate are moved along with the translation member so as to be
adjusted to specific positions.
3. The switching mechanism of claim 2, wherein a lens is disposed
in front of the filter or the glass plate, and an image capture
device and a printed circuit board are disposed behind the filter
or the glass plate.
4. The switching mechanism of claim 3, wherein the image capture
device is a CCD sensing element.
5. The switching mechanism of claim 3, wherein the image capture
device is a CMOS sensing element.
6. The switching mechanism of claim 1, wherein the driving device
is a motor.
7. The switching mechanism of claim 1, wherein the rack of the
translation member has a plurality of teeth, each tooth formed with
rounded upper and lower edges.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] The present invention relates to switching mechanisms
applicable to cameras. More particularly, the present invention
relates to a structurally simple, low-noise, and low wear-and-tear
mechanism for switching the filters of a camera without using
complex control and feedback units.
[0003] 2. Description of Related Art
[0004] For a general camera equipped with a CCD or CMOS sensing
element to maintain a satisfactory image-capturing state in the
daytime as well as at night, it is necessary to switch filters for
diurnal and nocturnal use of the camera respectively so that high
image fidelity is achieved in the daytime, and clear pictures can
be taken during the nighttime. Therefore, filter-switching
mechanisms are commonly provided in cameras.
[0005] A variety of filter-switching mechanisms are now available
on the market. These mechanisms can be divided, by the control
methods involved, into the following two types.
[0006] The "closed-circuit control mechanisms" are the most basic
and popular automatic switching mechanisms. In such a mechanism, be
it used in a mechanical, electronic, or optical device, sensors are
provided at a starting point and a terminal point of the switching
operation so as to detect the object being switched and feed back
electronic signals to a control chip, which then actuates or stops
a driving device (usually a motor) accordingly, thereby realizing
the desired switching function. When the object driven by the motor
reaches a predetermined position or condition, a signal is fed back
to the control chip so as to adjust the operation of the motor.
While this control method monitors the conditions of the object
being switched and provides reliable control over the object, it is
nevertheless disadvantaged by high costs and bulky design.
[0007] On the other hand, in an "open-circuit control mechanism",
an input unit provides one-way positive control over a motor so
that the motor drives an object without detecting its conditions.
Mechanisms of this type are advantageously simple and economical
because no special controllers and feedback mechanisms are
required. However, since there are no position sensing devices
(e.g., switches and sensors) for detecting the conditions of the
driven object, once the object is blocked from moving but the
driving device (e.g., a motor) is not timely stopped, components
along the driving link, such as the motor or a transmission
mechanism (most probably the motor), will be damaged. Therefore, in
order to protect the components, it is necessary to incorporate
into the control mechanism a mechanism for making and breaking the
connection between the driven object and the driving device. One of
the most popular solutions involves providing control by frictional
constraint. While this friction-based solution is mechanically
simple and economical, it has such inherent and unconquerable
defects as blindness toward the conditions of the driven object and
significant operational noise.
[0008] Thus, there is a need for a novel switching mechanism that
is applicable to cameras and capable of eliminating all the above
problems.
BRIEF SUMMARY OF THE INVENTION
[0009] In view of the aforementioned need, the inventor of the
present invention contemplated, from the perspective of design, on
ways to maximize the advantages of the existing open-circuit
control mechanisms and overcome their defects such as low stability
and significant operational noise, so as to enhance the quality and
competitiveness of products using such mechanisms. According to the
concept of the present invention, a gear mechanism capable of both
rotation and translation is positioned perpendicular to a
translation member such that the gear mechanism capable of rotation
and translation is engageable with a rack of the translation member
so as to drive the translation member to move, thus forming a
highly stable, low-noise open-circuit control mechanism that is
conveniently applicable to various systems.
[0010] The first objective of the present invention is to provide a
switching mechanism for a camera, wherein the switching mechanism
is capable of actuating reciprocating motions within a specific
interval without the assistance of feedback signals so as to
realize an automatic switching function of the camera, and wherein
the switching mechanism features a simple structure, low noise, low
wear and tear, and economy of space and cost and works without
complex control and feedback units.
[0011] The second objective of the present invention is to provide
a switching mechanism for a camera, wherein components of the
switching mechanism are easy to design and highly applicable.
Beside, by virtue of a common and frequently used mechanism design,
the components of the switching mechanism are easily adjustable in
position by making and breaking an engagement between the
components, thus effectively preventing vibration, noise, and wear
which may otherwise result from friction between the
components.
[0012] In order to achieve the above and other objectives, the
present invention provides a switching mechanism for a camera,
wherein the switching mechanism includes: a control unit; a driving
device coupled with the control unit so as to be actuated thereby;
a first gear set coupled with the driving device; a second gear
coupled with the first gear set, wherein the second gear is
centrally and fixedly provided with a rotary shaft that has a shaft
hole formed with a plurality of threads; a spindle being
female-connected to the shaft hole of the second gear and which has
an axial surface formed with a plurality of outer threads
corresponding to the threads of the shaft hole so that the second
gear is movable along the spindle; and a translation member
positioned perpendicular to the spindle and provided with rack for
engaging with the second gear.
[0013] Therein, the driving device, when actuated by the control
unit, drives the first gear set. The first gear set then
threadingly drives the second gear not only to rotate, but also to
translate linearly along and relative to the spindle as the threads
formed on the shaft hole of the rotary shaft of the second gear
match with the outer threads formed on the surface of the spindle.
Through proper spatial arrangement, the second gear, once moved to
a first predetermined position along the spindle, engages with the
rack of the translation member so that the rack drives the
translation member to move perpendicular to the spindle. When
further moved to a second predetermined position along the spindle,
the second gear is disengaged from the rack of the translation
member so that the translation member stops moving.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0014] The invention as well as a preferred mode of use, further
objectives, and advantages thereof will be best understood by
referring to the following detailed description of an illustrative
embodiment in conjunction with the accompanying drawings,
wherein:
[0015] FIG. 1 illustrates various principles for achieving
reciprocating motions within a predetermined interval, wherein
"Type III" is adopted in a switching mechanism for a camera
according to the present invention;
[0016] FIGS. 2A and 2B are front and top views of a switching
mechanism for a camera according to a preferred embodiment of the
present invention; and
[0017] FIGS. 3A, 3B, 4A, 4B, 5A, and 5B are pairs of corresponding
front and top views showing operation of some components of the
switching mechanism according to the preferred embodiment of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] Before the present invention is described in detail, the
basic principle of the present invention is briefly stated. Please
refer to FIG. 1 for various principles for achieving reciprocating
motions within a predetermined interval between points A and B,
wherein the horizontal solid lines represent stable connections
between driving units and the corresponding driven units, the
horizontal dotted lines represent unstable connections between the
driving unit and the corresponding driven unit, and the vertical
dashed lines indicate corresponding positions along a direction of
linear motion. A mechanism capable of such reciprocating motions
can be used to convey an object back and forth or serve directly as
a switching mechanism. In order to express the motion of a driving
unit (e.g., a motor), S denotes a starting point of energy input,
and E denotes a terminal point of the energy input. The entire
process is controlled by the operation time of the driving
unit.
[0019] As shown in FIG. 1, there are three alternative principles
for enabling reciprocating motions of a driven unit without using
feedback control elements. The three principles are referred to as
"Type I", "Type II", and "Type III" in the following
description.
[0020] "Type I" refers to a connection between driving and driven
units that is breakable at any time during operation, as indicated
by the horizontal dotted lines in the drawing. In this type of
connection, the driven unit will be retained at a specific
position, such as points A and B in the drawing, whenever a
constraining factor based on resilience or friction is applied to
the driven unit. However, since the "Type I" connection works on an
unstable kinematic relation between the driving and driven units,
it suffers from unintentional detachment, frictional noise, and
frictional wear, among other problems, and in consequence the
service life of the entire mechanism is reduced.
[0021] In the "Type II" connection, while the driving and driven
units are constantly connected to each other during operation, the
driven unit is completely constrained by the driving unit within a
specific interval, as indicated by the horizontal solid lines in
the drawing. Therefore, when the driven unit is moved in the
interval between points A and B, it is under total control of the
driving unit, and a highly reliable motion control mechanism is
thus achieved.
[0022] In the "Type III" connection, which provides the most
precise control among the three types, the driving unit is
connected with the driven unit only when the driven unit needs to
be driven, thus eliminating the problems related to unstable
connection. The "Type III" connection incorporates the advantages
of "Type I" and "Type II" and is adopted as the fundamental design
principle of the present invention.
[0023] In order to provide, under the premise that no feedback
control elements are required, a mechanism capable of reciprocating
motions within a predetermined interval, the inventor of the
present invention uses a first gear set, a second gear, and a
spindle of the second gear as driving units, and a translation
member provided with a rack, as a driven unit, wherein the driving
and driven units are arranged in a particular vertical
configuration so that the aforesaid objectives of the present
invention are achieved through engagement and disengagement between
the rack and the second gear. The concept of the present invention
is hereinafter demonstrated with a preferred embodiment, which is
now described in detail in conjunction with the accompanying
drawings.
[0024] FIGS. 2A and 2B are front and top views of a switching
mechanism for a camera according to the preferred embodiment of the
present invention. As shown in the drawings, the switching
mechanism comprises: a printed circuit board 110; an image capture
device 112 and a control unit 115 which are both mounted on the
printed circuit board 110; a driving device (e.g., a drive motor)
120 which is coupled with and actuated by the control unit 115; a
first gear set 130 which is coupled with the driving device 120 and
driven thereby to rotate; a second gear 140 which is coupled with
the first gear set 130 and is centrally and fixedly provided with a
rotary shaft 145, wherein the rotary shaft 145 has a shaft hole
whose surface is formed with a plurality of threads (not shown); a
spindle 150 female-connected to the shaft hole of the rotary shaft
145 of the second gear 140, wherein the spindle 150 has an axial
surface formed with a plurality of outer threads (not shown)
corresponding to the threads of the shaft hole of the rotary shaft
145 so that the second gear 140 is movable along the spindle 150;
and a translation member 160 which is positioned perpendicular to
the spindle 150 and provided with a rack 165 for engaging with the
second gear 140, wherein the translation member 160 is further
coupled with a glass plate 170 and a filter 180 while a lens 190 is
disposed in front of the filter 180.
[0025] When actuated by the control unit 115, the drive motor 120
drives the first gear set 130 to rotate. Then, the first gear set
130 threadingly drives the second gear 140 to rotate as well as to
move linearly along the spindle 150 as the threads of the shaft
hole of the rotary shaft 145 of the second gear 140 match with the
outer threads on the surface of the spindle 150. With proper
spatial arrangement, the second gear 140, when moved to a first
predetermined position along the spindle 150, contacts and then
engages with the rack 165 of the translation member 160, thus
driving the rack 165 to move linearly and perpendicularly to the
spindle 150. As a result, the rack 165 drives the translation
member 160 to move along. When the second gear 140 is further moved
to a second predetermined position along the spindle 150, the
second gear 140 is disengaged from the rack 165 of the translation
member 160 so that the rack 165 stops moving, and in consequence
the translation member 160 stops moving, too.
[0026] As the translation member 160 is coupled with the filter 180
and the glass plate 170, when the translation member 160 is driven
by the rack 165 to move, the filter 180 and the glass plate 170 are
also moved linearly with the translation member 160 so as to be
adjusted to specific positions. The image capture device 112
coupled with the printed circuit board 110 can be either a CCD
sending element or a CMOS sensing element.
[0027] A more detailed description by stages of how the driving
units (i.e., the drive motor 120, the first gear set 130, the
second gear 140, and the spindle 150) drive the driven unit (i.e.,
the translation member 160) for linear translation is now provided
by reference to FIGS. 3A, 3B, 4A, 4B 5A, and 5B, which show pairs
of corresponding front and top views of the switching mechanism for
a camera according to the preferred embodiment of the present
invention.
[0028] To begin with, as shown in FIGS. 3A and 3B, the drive motor
120 is activated by voltage input from the control unit 115 and
drives the first gear set 130 to rotate. The second gear 140, which
is coupled with the first gear set 130 and capable of both rotation
and translation, is therefore driven threadingly by the first gear
set 130 to rotate with the first gear set 130. Meanwhile, the
rotary shaft 145 centrally and fixedly provided on the second gear
140 also rotates with the first gear set 130. Since the shaft hole
of the rotary shaft 145 of the second gear 140 is female-connected
to the spindle 150, and the threads of the shaft hole of the rotary
shaft 145 of the second gear 140 correspond to the outer threads on
the surface of the spindle 150, the second gear 140 is driven via
the matching of the threads to move linearly along and relative to
the spindle 150. At this stage, the rack 165 of the translation
member 160 is not engaged with the second gear 140 so that the rack
165 does not move perpendicular to the spindle 150. In consequence,
the translation member 160 is also not driven to move.
[0029] Afterward, referring to FIGS. 4A and 4B, as the first gear
set 130 continues driving the second gear 140, and the threads on
the surface of the spindle 150 keep matching with the threads of
the shaft hole of the rotary shaft 145 of the second gear 140, the
linear motion of the second gear 140 along the spindle 150 goes on.
Upon reaching the first predetermined position along the spindle
150, the second gear 140 contacts and then engages with the rack
165 of the translation member 160, thus driving the rack 165 to
move linearly and perpendicular to the spindle 150. As a result,
the translation member 160 on which the rack 165 is provided moves
linearly with the rack 165.
[0030] Referring to FIGS. 5A and 5B, the drive motor 120 keeps
driving the first reduction gear set 130 to rotate so that the
first gear set 130 keeps driving the second gear 140 to rotate as
well as to translate linearly along the spindle 150. In the
meantime, as the second gear 140 continues driving the rack 165 of
the translation member 160, the rack 165 keeps on translating
perpendicular to the spindle 150. When the second gear 140 reaches
a second predetermined position along the spindle 150, the
engagement between the rack 165 and the second gear 140 comes to a
final stage. From then on, the second gear 140 gradually disengages
from the rack 165 and eventually is disengaged completely
therefrom. The rack 165 then stops translation and enters a static
state, thus concluding the translation of the translation member
160.
[0031] According to the above description, a linear motion
controlled and constrained by a driving unit is realized through
the relative position between the second gear 140 and the rack 165
of the translation member 160. When the driving unit (i.e., the
drive motor 120) is controlled by the control unit 115 to move in a
reverse direction, all subsequent motions take place in reverse
directions. In so doing, an open-circuit reciprocating mechanism is
accomplished, and the intended objectives of the present invention,
achieved.
[0032] To facilitate engagement between the second gear 140 and the
rack 165, the rack 165 may have teeth each formed with rounded
upper and lower edges so as to enable smooth engagement. By
facilitating the engagement and disengagement between the second
gear 140 and the rack 165, the noise, vibration, and wear resulting
from such engagement and disengagement are also minimized.
[0033] A simple mechanism derived from the inventor's ample
experience and ingenious concept is herein provided for fully
solving the problems of the prior art, and the inventor believes
that the functions of the disclosed subject matter meet the
requirement of novelty and non-obviousness for patent
application.
[0034] While the present invention is demonstrated herein by
reference to the preferred embodiment, it is understood that the
disclosed embodiment is not to limit the scope of the present
invention. Therefore, all equivalent changes or modifications that
are based on the appended claims and do not depart from the essence
and concept of the present invention should be construed as further
embodiments of the present invention.
* * * * *